drm/amdgpu: fix memory overflow in the IB test

stable inclusion
from stable-v6.6.5
commit 6dfccebfecc4b99f64d25351bb6ac69f1a6926e2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8N21P

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6dfccebfecc4b99f64d25351bb6ac69f1a6926e2



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commit 6b0b7789a7a5f3e69185449f891beea58e563f9b upstream.

Fix a memory overflow issue in the gfx IB test
for some ASICs. At least 20 bytes are needed for
the IB test packet.

v2: correct code indentation errors. (Christian)

Signed-off-by: Tim Huang <Tim.Huang@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>